Embodiments of the present invention comprise a method for creating pre-stressed zones in concrete. In one embodiment, a circular blade is coated with a chemical which retards the setting of the concrete. The circular blade is then rolled through the wet concrete, thus transferring the retarding chemical from the blade into the concrete. The region of wet concrete that has the retarding chemical introduced into it does not set until after the surrounding concrete has set and shrunk, thus creating a pre-stressed zone which typically manifests itself as a crack, visible upon setting of the wet concrete. Other embodiments describe alternative ways of introducing the chemical into the wet concrete.